1. Field of Invention
The present invention relates to a user-interface and, more specifically, a character selection interface system for entering ambiguous text input on input- and/or display-constrained devices with or without a keypad where character/symbol clusters are linearly rendered on a device display and are navigable in a single dimension.
2. Description of Related Art
Linear text input systems are those that require a user to input each letter of the text by scrolling through a selection of characters and selecting the desired character. Such interfaces are useful on devices that do not have a keypad, or have a constrained input keypad, e.g., iPod devices or car navigation systems. FIG. 1 illustrates one such linear text input system for entering unambiguous text. In FIG. 1, the user has selected “A”, followed by “R”, and is currently in the process of scrolling through numerals 0-9 and letters A-Z to select the next character in the input string.
Any user of linear text input systems is painfully aware of the overshoot/undershoot problem. Because linear text input systems require the user to scroll through a long list of characters, overshoot tends to occur when user selects characters separated by a relatively large number of characters. For example, a user may rapidly click the navigation buttons or hold the navigation buttons down when moving from one character to the next, where the characters are far apart in the list. However, overshoot can also occur with characters that are close together in the list, as the user may simply click the navigation button too many times, or hold the button down for too long. Undershoot can occur in a similar circumstance, when the user clicks too few times or does not hold the button down long enough to scroll through the appropriate number of characters.
Thus, users tend to slow down and carefully select the item of choice when getting close to the desired item. This increases the amount of time required for a user to enter text. Furthermore, navigation of a linear alphabet for character selection can become cumbersome since the navigation length is on average high. For example, the English alphabet along with numbers would be a list of 36 characters. Text input by navigating to each character becomes extremely cumbersome.